You will need access to a hand drill with bits of different sizes. See the Materials and
Equipment list for details.

Cost

Low ($20 - $50)

Safety

Use caution when using a drill. Be sure to wear safety goggles. Adult supervision is recommended.

Abstract

People often call cardiovascular disease a "silent killer." This disease sneaks up and causes damage,
but patients don't realize it—until serious symptoms start. That is why physicians recommend keeping
your cardiovascular system healthy. A healthy cardiovascular system gives us the energy and the stamina
to do all of the things that we want to accomplish, such as do our best in school and perform well in sports.
But what makes a cardiovascular system unhealthy, and what are the factors that lead to problems like poor
blood flow rate? In this life science project, you will build a model of the heart and the arteries with a
bucket, tubes, and water to see what affects blood (water) flow rate. You will see what it takes to maintain
a healthy heart and arteries.

Objective

Build a model of the human cardiovascular system, and investigate the effect of changing the diameter
of an artery, due to disease, on blood flow rate.

Credits

Michelle Maranowski, PhD, Science Buddies

Edited by Colleen Callaghan, MD

This science project idea is based on this 2010 California State Science Fair entry:
Balasingam, Namrata. (2010). On the Rate of Flow of Liquids in Tubes and Its Implications to Cardiovascular
Health.

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Introduction

The human body is made up of several systems that work together to keep the body functioning
properly. One of these systems is called the cardiovascular system. The job of the
cardiovascular system is to move blood, which contains oxygen and nutrients, throughout the
body to the different organs and the brain. The cardiovascular system is made up of the heart,
arteries,capillaries, and veins. For the purpose of this project, let us
focus on the heart and arteries.

The heart is a muscle that acts as the pump of the cardiovascular system. The
heart is divided into the right and the left sides. Each side has two chambers, an atrium
and a ventricle. The right side of the heart pumps oxygen-poor blood to the lungs where the
lungs deliver oxygen to the blood. The oxygen-rich blood comes back to the left side of the heart
into the left atrium and empties into the left ventricle. From there, the heart pumps the blood
through the aorta, the largest artery in the body, to supply the organs and the brain with
oxygen and other nutrients. Valves separate the atrium and ventricle on each side of the heart. The
valves make sure to keep the blood flowing in the right direction. Because the right side and the left
side of the heart are not connected, the oxygen-poor blood does not mix with the oxygen-rich blood. The
heart muscle itself also needs oxygen to function properly. A network of coronary arteries covers
the heart and provides it with oxygenated blood. Watch this video to understand the details of how the
heart works.

Interested in learning how the heart and the circulatory system work? View this video from the Mayo Clinic that illustrates what makes your heart tick. (Courtesy of the Mayo Clinic. (2009).)

A healthy cardiovascular system is very important to maintain good health. Failing to maintain
good cardiovascular health can result in heart disease or atherosclerosis. In atherosclerosis,
cholesterol, fatty substances, calcium, and other substances start to build up in the inner lining of
an artery. This buildup, called plaque, leads to a narrowing (smaller diameter) of the
artery. If a plaque breaks, it can cause a blood clot to start. A blood clot can block blood
flow or can travel to a different part of the body. Depending on where the clot occurs, it can cause a
heart attack or a stroke. A heart attack or stroke is a very dangerous health problem, but even plaque
that stays put can cause issues by contributing to poor blood flow. Poor blood flow can cause chest pains,
high blood pressure, shortness of breath during light exercise, leg pain, and loss of oxygen to the brain.

In this life science project, you will make a model of the cardiovascular system and investigate if plaque
or narrowing in the arteries affects flow rate. You will make the model with a bucket, valves, and vinyl
tubing of different diameters. Does the flow rate depend on the diameter of the tubing? If so, how much
does the flow rate change?

Terms and Concepts

Cardiovascular

Artery

Capillary

Vein

Muscle

Pump

Atrium

Ventricle

Aorta

Coronary

Atherosclerosis

Plaque

Blood clot

Absolute value

Magnitude

Density

Hagen-Poiseuille equation

Questions

What causes your heart to beat?

What are the four different heart valves?

What can happen to your brain if blood doesn't flow to it?

What happens to your body during a heart attack?

What is plaque made of?

What can happen to your legs if there isn't enough blood flow to them?

Bibliography

These websites offer more information about the cardiovascular system and blood flow rate:

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Experimental Procedure

Building the Model of the Circulatory System

Drill two holes in the bucket. Place each hole 3 inches from the bottom of the bucket. Drill the holes
on opposite sides of the bucket from each other.

Use goggles and ask an adult for help when drilling holes in the bucket.

Drill the first hole with the 1/4 inch bit.

Drill the second hole with the 3/8 inch bit.

Insert and screw the threaded male end of the 1/4 inch valve into the 1/4 inch hole in the bucket.

Insert and screw the threaded male end of the 3/8 inch valve into the 3/8 inch hole on the other side of
the bucket.

Make sure that the valves are all shut, and then, test to make sure that the valves are not leaking. Fill
the bucket with water to a level above the height of the valves. If they are leaking, then use some plumber's
putty to seal the leak on the outside of the bucket.

Cut two lengths of tubing with the utility knife. Cut 2 feet of 1/4 inch diameter tubing, and insert it into
the free end of the 1/4 inch valve.

Repeat step 5 with the 3/8 inch vinyl tubing and the 3/8 inch valves.

The model is now complete. Leak test the finished model as in step 4. Once the model is leak free, proceed
to the next section and start experimenting.

Experimenting with the Circulatory Model

Fill the bucket with water to a level that is above the valves. Mark the level of the water on the outside
of the bucket with a permanent ink marker.

Place the model on the table. Ask an adult for help if the bucket is too heavy. Set the bucket so that
the 1/4 inch valve and tubing is over the edge of the table. Place the tubing in the measuring cup. If you
can't place the measuring cup on the floor without making a puddle, place it on a second table that is lower
than the one that the bucket is on. Make sure that the tubing hangs straight down and doesn't get angled or
pinched.

If you have a video camera, place it on a table (or tripod) facing the measuring cup. The camera should
be close enough that you are able to read the markings on the measuring cup.

When you are ready to start experimenting, turn on the camera.

Now open the valve and start the stopwatch. When the measuring cup is filled with a 1/2 cup of water, turn
off the stopwatch and the valve. Record the time in your lab notebook along with the amount of water in the
measuring cup.

Repeat step 5 four more times (four more trials for a total of five trials). Refill to the original fill
line each time. It is important to repeat your experiments to ensure that your results are reproducible and
accurate.

Turn off the camera. Clean up any excess water and pour the water from the measuring cup back into the
bucket. Refill the bucket, if necessary, to the mark on the bucket.

Turn the bucket so that the 3/8 inch valve and tubing is over the edge of the table.

Repeat steps 3–7 with the 3/8 inch valve and tubing.

Empty the bucket.

Analyzing Your Data

Now calculate the flow rate for each trial of each diameter of tubing. Calculate the flow rate by
dividing the volume of water in the cup, 1/2 cup, by the time it took in seconds to fill the measuring
cup to a 1/2 cup. If you used a video camera to film the experiment you can watch the video to get a
precise time of when the 1/2 cup was filled.

Figure out how to move frame by frame to retrieve a precise time measurement.

Plot your data on a scatter plot. Can you see any trends in your data?

Average the data for each diameter of tubing. Calculate the percent difference in flow rate between
the different diameters of tubing. Equation 1 describes how to calculate the percentage difference in
flow rate. Absolute value takes the magnitude of a number. For example, the absolute
value of -6 is 6.

Equation 1.

Percent difference (%) =

absolute value |flowrateA - flowrateB| flowrateA

× 100

flowrateA= flow rate at the 3/8 inch valve

flowrateB= flow rate at the 1/4 inch valve

Based on your results, how does a narrowed vessel affect the flow rate of blood? What are the implications
for cardiovascular health?

Communicating Your Results: Start Planning Your Display Board

Create an award-winning display board with tips and design ideas from the experts at ArtSkills.

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Variations

Does blood pressure affect the flow rate? Experiment with this variable by changing the starting level
of the water in the bucket. The pressure at the valve is equal to the density of water multiplied
by the difference in height between the surface of the water and the valve.

Does the length of the tubing affect flow rate? Experiment with two additional lengths of tubing for
both valves.

Looking at your results as a whole, can you confirm whether the Hagen-Poiseuille equation is satisfied?

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Ask an Expert

The Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Related Links

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